Coating compositions containing paraffin wax, ethylene-vinyl acetate copolymer, and fischer-tropsch wax



Patented Sept. 3, 1968 United States Patent 0,400,002

h It has now been found that wax-based coatings pos- 0 'L sessing highgloss retention and excellent blocking and COATING COMPOSITIONSCONTAINING PARAF- picking characteristics can be prepared by the use ofcompositions comprising from 45 to 89.9% by weight of Richard C. Fdx,San Rafael, CaliL, assignor to Chevron 5 a paraffin wax havmg a meltingPoint In the range of Research Corporation, a corporation of Delaware140-1700 from 50% y Weight of a No Drawing. Filed Dec. 11, 19,64, Ser.No. 417,814 polymer of hyl ne a d vln-yl acetate and from 0.1 to

3 Claims. (Cl. 260-28.5) 15% by weight of a Fischer-Tropsch wax havingan average molecular weight between about 750 and 1,000.

The ethylene-vinyl acetate copolymers of U.S. Patent 2,877,196,previously cited, have a polymerized vinyl acetate content of from about5% to 25% by weight. Co-

ABSTRACT OF THE DISCLOSURE Coating composition having improved glossretention polymers containing vinyl acetate contents without that andresistance to blocking and picking consisting essenrange also y be p yfor p a copolymer tially of from 45 to 899% by Weight f a petroleum whaving a vinyl acetate content of about is marketed from 5 to 50% byweight of a copolymer of ethylene and is in common use in wax-basedcoatings. and vinyl acetate, and from 0.1 to 15% by weight of a TheFiSCher-TmPSeh WaXeS Which are p y as Fischer-Tropsch wax having anaverage molecular weight gloss-improving agents are waxes synthesized bythe fabetWeen about 750 and 1,000. miliar Fischer-Tropsch process. Inthis process, coal is 0 burned in a steam-oxygen atmosphere to producehydrogen and carbon monoxide, which substances are then reacted in thepresence of a catalyst to produce the de- This invention relates to waxbase coating compositions sired hydrocarbon -g- FiSehef-TI0P5eh Thesewhich display superior gloss retention and resistance to Waxes are p yin coating compositions in blocking and picking. More particularly, itis concerned amounts sumeieht enhance the 8105s retention Characwithcompositions comprising a petroleum wax, an ethyp teristics of thecoatings. Amounts of from 0.1 to 15 by ene-vinyl acetate copolymer andan additive especially Weight have been found to be generallyshfiieieht; effective in improving the gloss retention ability of theamounts of from 3 t0 5% y Weight are Preferredcompositions. The waxeswhich are employed in the compositions It ha lo bee common ti to employwax d of this invention are petroleum waxes, and more prefer- Wax-basedcompositions to coat such articles of commerce ably, PredominantlyParaffih WaXeS- The Waxes Should as paper, paper board milk cartons,food, cardboard, etc. melt 111 the range of More P The coatings areapplied to render containers moisturey, the WaXeS Should melt in a rangeof proof and thus adapted to hold liquids or liquid-contain wahesmelting below abeht Show a P ing materials. In addition to thewater-resistant property 81058 retention, and Waxes mehlhg above tend ofthe coatings, other highly important characteristics to have a muchhigher gloss retention factor than the which the coatings should possessare high tensile strength 145-165 0 W and high gloss, Which lends anattractive pp aranc The following examples illustrate the wax-based coath coated articleh ing compositions which are employed in this invention.

The examples are, of course, nonlimiting.

It is known that the addition of copolymers of ethyl! ene and vinylacetate to petroleum waxes results in coating compositions of hightensile strength and ductility. Example I U 8. Patent 2,877,196discloses such compositions con- In these tests panels from h 1f 11 milkcartons talhlhg from b to about 20% by welgbt of were coated with thewax blends. The wax employed was copolymers. Even higher amounts of thecopolymers have one having a melting point f about F p The been employedwith qhahthiee as high as by we 'Fischer-Tropsch Wax used was one havinga molecular being used. Especially effective coatings are those thatweight range of 750 to 1,000 The temperature f the contain about 30% byweight of an ethylene-vinyl acetate coatings at time f coating Was2404800 R Aft coat. copolymer. I -Iowever, it has been found that thecomposi- 50 m the Panels were dipped into wateh Then, one hens, p e -y hthe Wax base 15 employed, 1S of each set was placed into a constanthumidity box huddle mehlhh P h range -a 1494700 maintained at 73 F. andone each of the other set placed J mehlhg Polht, tend to dlsplay aeighlfieaht 1033 into a constant heat box maintained at 115 F. Gloss Ofinitial glOSS when coated materials are StOl'fid. F01 CX- reading weretaken of the am les at intervals employample, dairy eehtah'lefmaterials, bfehd PP g -0 ing a Gardner gloss meter with a standardsetting of 100. are often stored for considerable periods before use. ItTh d t f these tests i compiled i T b1 I f ll is thus highly importantfor appearance that the high ing:

TABLE I Ethylene- Fiseher- Exposure Days Sample No. Vinyl acetate,Tropsch Temp,

Percent Wax, Percent 1 2 3 3 5 6 7 8 9 10 11 12 13 14 15 16 l7 1B 19 2021 Gloss after Exposure gloss of the coating be retained during thestorage 196- As shown by the data of Table I, the Fischer-Tropsch riod.This gloss diminution is especially significant 1n waxes improve thegloss retention of the compositions the materials Containing about 30%of the ethylene-vlnyl without significant lowering of the initial glosslevels.

acetate copolymers, however, the problem arises also with compositionsin which the copolymers are present in a 70 Example II wide range, i.e.,5 to 45%, by weight. In addition to the increase in gloss retentionlevels, an

increase in seal strength, blocking and picking temperature results fromthe addition of the additives of this invention.

In the following tests, paper strips were coated with wax blends, andblocking points and picking points of the compositions were determined.The blocking and picking points were ascertained by the method of ASTMD1465-57T with samples being run in duplicate. In general, the pointsare measures of the tendency of slabs of wax-coated papers to adhere toeach other. The picking point is the temperature at which the first filmdisruption occurs on the waxed paper. The blocking point is thetemperature at which 50% of the film is disrupted.

The waxes which were tested were paraffin waxes as indicated in thetable; the additives are the same as employed in Example I with theFischer-Tropsch wax of Example II indicated as G.

4 of this invention to wax-ethylene vinyl acetate compositions.

Other additives common to wax coatings, such as oxidation inhibitors,etc., may be employed in the composition of this invention.

I claim:

1. A composition of matter consisting essentially of from 45 to 89.9% byweight of a paraffin wax having an average melting point in the range of140 to 170 F. A.M.P., from 5 to 50% by weight of a copolymer of ethyleneand vinyl acetate having a vinyl acetate content between about 5 and25%, and from 3 to 15% by weight of a Fischer-Tropsch wax having anaverage molecular weight between about 750 and 1,000.

2. The composition of claim 1 wherein the parafiin wax has an averagemelting point in the range of 145- 165 F. A.M.P.

Additive, Blocking Picking percent Point, F. Point, F.

"'iri 4 5 i 159 142 1 Total (tore at room temperature).

Thus, these data show that, in addition to gloss retention improvements,a marked increase in blocking and picking points results from theaddition of the additives 3. The composition of claim 1 wherein thecopolymer of ethylene and vinyl acetate is present in an amount of 25 to35% by weight.

References Cited UNITED STATES PATENTS 3,102,040 8/1963 Williams et a1.106270 3,175,986 3/1965 Apikos et a1. 26028.5 3,189,573 6/1965 Oken26028.5 3,215,657 11/1965 Beresniewicz et al. 26028.5

OTHER REFERENCES Warth: Chemistry and Technology of Waxes, 2d edition,Reinhold Pub. Corp., N.Y., 1956, pp. 791-792.

MORRIS LIEBMAN, Primary Examiner.

B. A. AMERNICK, Assistant Examiner.

